Phoenix was Tezuka's life work as well as one of his representative works. He explored philosophical themes of "life and death" and "reincarnation" in depth by depicting stories developed around Phoenix, the immortal life-form beyond time and space. Phoenix navigates the readers by traveling back and forth, between past and future, through the series. Tezuka reflected his own historical view and prevision for future, also tackled a vast-scale question of what universe is.